I've got an Atwood 7920 in my 2001 Coleman pup. It starts up fine, puts out good heat, but when I first start it, it screams, or squeaks. It sounds like the fan squealing, but I disassembled the unit and the fan isn't making the noise. Thing is, after a while of running the noise stopped Saturday. We have warm days forecast this week so I probably won't be able to run it again until the weekend. Any idea why I get this noise?